I am working on a residing project for a friend. We are stripping to the studs, insulating, resheathing, and covering with 3/4 foam board, tyvek, and then hardie. In a couple sections I am resheathed and have a couple questions. When I flash the windows with vycor or similar I am trying to decide where to apply. I have flashed below the tyvek, directly to the sheathing in the past. If I do that now, I would apply to the plywood, and then add foam board and tyvek. Other option would be to apply the flashing above the tyvek as is commonly done in new construction. My other question is if vycor or a similar product is good to use for air sealing plywood seams under the foam board. I have seen a specific sheathing sealing tape, but it is not readily available locally. Thanks!